Curable composition, coating liquid, coating film, and laminate

Abstract

The present invention provides a curable composition that can form a coating film with high hardness and excellent scratch resistance. [Solution] The curable composition of the present invention comprises a urethane acrylate compound and inorganic fine particles, wherein the urethane acrylate compound is an addition product of an isocyanate and at least one hydroxyl group-containing compound, the isocyanate is a bifunctional or trifunctional isocyanate compound, the hydroxyl group-containing compound has at least two (meth)acryloyl groups and at least one hydroxyl group in its molecule, the inorganic fine particles have polymerizable unsaturated groups on their surface, and the median particle size of the inorganic fine particles is 15 to 75 nm.

Description

Technical Field

[0001] The present invention relates to a curable composition, a coating solution, a coating film, and a laminate.

Background Art

[0002] A curable composition contains a polymerizable component that is cured by active energy rays such as ultraviolet rays, and can form a cured product such as a coating film by curing, so it is widely used for coating applications on the surface of a substrate such as a resin film.

[0003] Specifically, a coating film can be formed on the surface of a substrate by applying a curable composition to the surface of a substrate used in an electronic device, an optical device, etc. and curing it. Such a coating film protects the surface of the substrate, for example, preventing damage to the surface of the substrate. In recent years, various curable compositions that can form a coating film excellent in performance such as scratch resistance have been studied in order to improve the protection performance of the surface of a substrate such as a resin film.

[0004] For example, Patent Document 1 discloses an active energy ray curable composition containing a urethane acrylate resin having a specific structure and a photoinitiator, and it is said that such a composition can form a cured coating film having high hardness and excellent scratch resistance.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in recent years, as the performance of electronic and optical devices has rapidly improved, the demand for further performance improvements in substrates such as resin films used in them has been increasing. Accordingly, there has been a growing demand for improved performance in curable compositions (coating agents) used to form the aforementioned coating film on the substrate surface, and in particular, there has been a need for curable compositions that can form a coating film that is harder and more scratch-resistant than conventional compositions.

[0007] The present invention has been made in view of the above, and aims to provide a curable composition that can form a coating film having high hardness and excellent scratch resistance. The present invention also aims to provide a coating liquid containing the curable composition and a laminate comprising a coating film formed using the coating liquid. [Means for solving the problem]

[0008] The inventors of this invention conducted extensive research to achieve the above objectives and, as a result, discovered that the above objectives can be achieved by using a urethane acrylate compound having a predetermined structure and inorganic fine particles as essential components, thus completing the present invention.

[0009] In other words, the present invention encompasses, for example, the subject matter described in the following sections. Item 1 A curable composition comprising a urethane acrylate compound and inorganic fine particles, The urethane acrylate compound is an addition reaction product of an isocyanate and at least one hydroxyl group-containing compound. The isocyanate is a bifunctional or trifunctional isocyanate compound. The hydroxyl group-containing compound has at least two (meth)acryloyl groups and at least one hydroxyl group in its molecule. The inorganic fine particles have polymerizable unsaturated groups on their surface, A curable composition in which the median particle size of the inorganic fine particles is 15 to 75 nm. Section 2 The curable composition according to claim 1, wherein the hydroxyl group-containing compound has a skeleton in its molecule derived from one or more compounds selected from the group consisting of pentaerythritol and dipentaerythritol. Section 3 The curable composition according to item 1 or 2, further comprising an acrylate compound that does not contain a hydroxyl group. Section 4 The curable composition according to claim 3, wherein the acrylate compound that does not contain a hydroxyl group has a skeleton in its molecule derived from one or more compounds selected from the group consisting of pentaerythritol and dipentaerythritol. Section 5 A coating liquid containing the curable composition described in any one of items 1 to 4. Section 6 A coating film containing a cured product of the coating liquid described in item 5. Section 7 The coating film according to claim 6, wherein the cured product contains a polymer of the urethane acrylate compound and the inorganic fine particles. Section 8 A laminate comprising a coating film as described in item 7 on a substrate. Section 9 A method for producing a curable composition according to any one of items 1 to 4, A method for producing a curable composition, comprising the step of obtaining the urethane acrylate compound by performing an addition reaction between the isocyanate and an alcohol component containing the hydroxyl group-containing compound. [Effects of the Invention]

[0010] The curable composition of the present invention can form a coating film that has high hardness and excellent scratch resistance. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below. In this specification, the expressions "containing" and "including" include the concepts of "containing," "including," "substantially consisting of," and "consisting only of."

[0012] In the numerical ranges described step by step in this specification, the upper limit value or lower limit value of a numerical range at a certain step can be arbitrarily combined with the upper limit value or lower limit value of a numerical range at another step. In the numerical ranges described in this specification, the upper limit value or lower limit value of the numerical range may be replaced with the value shown in the examples or a value uniquely derived from the examples. Also, in this specification, numerical values connected by "~" mean a numerical range including the numerical values before and after "~" as the lower limit value and the upper limit value.

[0013] 1.Curable composition The curable composition of the present invention contains a urethane acrylate compound and inorganic fine particles as essential components. In the curable composition of the present invention, the urethane acrylate compound is an addition reaction product of an isocyanate and at least one hydroxyl group-containing compound. The isocyanate is a bifunctional or trifunctional isocyanate compound, and the hydroxyl group-containing compound has at least two or more (meth)acryloyl groups and at least one or more hydroxyl groups in the molecule. Further, the inorganic fine particles have a polymerizable unsaturated group on the surface, and the median particle diameter of the inorganic fine particles is 15 to 75 nm.

[0014] The curable composition of the present invention has high hardness and can form a coating film excellent in scratch resistance. In particular, the coating film obtained from the curable composition of the present invention has high Martens hardness and pencil hardness. Also, by providing the coating film obtained from the curable composition of the present invention on a substrate, it becomes easy to prevent such a substrate from curling. Therefore, the curable composition of the present invention can be suitably used as a coating liquid (coating agent) for substrates such as resin films.

[0015] The urethane acrylate compound contained in the curable composition of the present invention is a product (addition reaction product) obtained by an addition reaction of an isocyanate and at least one hydroxyl group-containing compound. More specifically, in the present invention, an addition reaction is carried out using an isocyanate and an alcohol component containing at least one hydroxyl group-containing compound as raw materials. By this addition reaction, the isocyanate and at least one hydroxyl group-containing compound in the alcohol component undergo an addition reaction, and the addition reaction product is obtained as a urethane acrylate compound.

[0016] (Isocyanate) The isocyanate is a bifunctional or trifunctional isocyanate compound. That is, the isocyanate is a compound having two or three isocyanate groups in the molecule. Therefore, the isocyanate is more specifically a polyisocyanate.

[0017] As long as the isocyanate is a compound having two or three isocyanate groups in the molecule, its type is not particularly limited, and for example, known isocyanate compounds can be widely cited.

[0018] The isocyanate is preferably at least one selected from the group consisting of aliphatic isocyanates and their derivatives, alicyclic isocyanates and their derivatives, and aromatic isocyanates and their derivatives. It should be noted that both aliphatic isocyanates and their derivatives (aliphatic isocyanate derivatives) preferably do not have an aromatic ring or an alicyclic ring (cyclic hydrocarbon group) in the molecule.

[0019] Examples of the aliphatic isocyanate include aliphatic diisocyanate compounds having 30 or fewer carbon atoms. Specific examples of aliphatic isocyanates include ethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, and 2,2,4-trimethyl-1,6-hexamethylene diisocyanate. In terms of the ease with which the hardness of the coating film obtained from the curable composition of the present invention can be increased and the scratch resistance can be further improved, the aliphatic isocyanate is preferably an aliphatic diisocyanate compound having 4 to 30 carbon atoms, and more preferably an aliphatic diisocyanate compound having 4 to 10 carbon atoms.

[0020] The aliphatic isocyanate derivative is preferably at least one selected from the group consisting of isocyanurates and biuretes of aliphatic polyisocyanates, as this tends to increase the hardness of the coating film obtained from the curable composition of the present invention and further enhances scratch resistance.

[0021] Examples of isocyanurate derivatives of aliphatic polyisocyanates include compounds in which -R-NCO is bonded to a nitrogen atom derived from isocyanurate, and examples of biuret derivatives of aliphatic polyisocyanates include compounds in which -R-NCO is bonded to a nitrogen atom derived from biuret. Here, R can be an alkylene group having 30 or fewer carbon atoms, preferably an alkylene group having 4 to 30 carbon atoms, and more preferably an alkylene group having 4 to 10 carbon atoms. A specific example of an aliphatic isocyanate derivative is "Coronate HX" (registered trademark) manufactured by Tosoh Corporation.

[0022] Examples of alicyclic isocyanates include isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (H12MDI), 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, and 1,3-bis(isocyanate methyl)cyclohexane.

[0023] Examples of aromatic isocyanates include tolylene diisocyanate (TDI), 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, and 1,4-phenylene diisocyanate.

[0024] The isocyanate is preferably an aliphatic isocyanate and its derivatives, more preferably an aliphatic isocyanate derivative, even more preferably an isocyanurate or biuret of an aliphatic polyisocyanate, and particularly preferably an isocyanurate of an aliphatic polyisocyanate. When the isocyanate includes an isocyanurate of an aliphatic polyisocyanate, the curable composition of the present invention tends to form a coating film with higher Martens hardness and better scratch resistance.

[0025] Urethane acrylate compounds can be obtained using one or more isocyanates. That is, urethane acrylate compounds may contain structural units derived from one or more isocyanates.

[0026] Isocyanates can be obtained by known manufacturing methods, or from commercially available products.

[0027] (Hydroxy group-containing compound) A hydroxyl group-containing compound is a compound having at least two (meth)acryloyl groups and at least one hydroxyl group in its molecule. Therefore, a hydroxyl group-containing compound is a radically polymerizable compound containing a hydroxyl group. Note that (meth)acryloyl group refers to either a methacryloyl group or an acryloyl group.

[0028] The hydroxyl group-containing compound may have three or more (meth)acryloyl groups, preferably ten or fewer, more preferably eight or fewer, and even more preferably six or fewer.

[0029] The number of hydroxyl groups in a hydroxyl group-containing compound may be one or two or more. For example, the number of hydroxyl groups in a hydroxyl group-containing compound is six or less, preferably five or less, more preferably four or less, and even more preferably three or less. The number of hydroxyl groups in a hydroxyl group-containing compound is particularly preferably one or two.

[0030] As long as a hydroxyl group-containing compound is a compound having at least two (meth)acryloyl groups and at least one hydroxyl group in its molecule, its type is not particularly limited, and a wide range of known hydroxyl group-containing compounds can be listed.

[0031] In particular, the hydroxyl group-containing compound preferably has a skeleton in its molecule derived from one or more compounds selected from the group consisting of pentaerythritol and dipentaerythritol. In this case, the curable composition of the present invention is more likely to form a coating film with higher Martens hardness and better scratch resistance. In particular, when the hydroxyl group-containing compound has a skeleton derived from dipentaerythritol in its molecule, the Martens hardness tends to increase even further, and the scratch resistance also becomes even better.

[0032] Furthermore, the skeleton derived from pentaerythritol within the molecule can refer to the skeleton formed by removing at least one hydrogen atom from the hydroxyl group of pentaerythritol, and the skeleton derived from dipentaerythritol within the molecule can refer to the skeleton formed by removing at least one hydrogen atom from the hydroxyl group of dipentaerythritol.

[0033] Specific examples of hydroxyl group-containing compounds include compounds in which the hydrogen atoms of two hydroxyl groups of pentaerythritol are each replaced by (meth)acryloyl groups, compounds in which the hydrogen atoms of three hydroxyl groups of pentaerythritol are each replaced by (meth)acryloyl groups, compounds in which the hydrogen atoms of two hydroxyl groups of dipentaerythritol are each replaced by (meth)acryloyl groups, compounds in which the hydrogen atoms of three hydroxyl groups of dipentaerythritol are each replaced by (meth)acryloyl groups, compounds in which the hydrogen atoms of four hydroxyl groups of dipentaerythritol are each replaced by (meth)acryloyl groups, and compounds in which the hydrogen atoms of five hydroxyl groups of dipentaerythritol are each replaced by (meth)acryloyl groups. In particular, the hydroxyl group-containing compound is preferably one or more selected from the group consisting of compounds in which two hydrogen atoms of the hydroxyl groups of pentaerythritol are each replaced by (meth)acryloyl groups, compounds in which three hydrogen atoms of the hydroxyl groups of pentaerythritol are each replaced by (meth)acryloyl groups, and compounds in which five hydrogen atoms of the hydroxyl groups of dipentaerythritol are each replaced by (meth)acryloyl groups.

[0034] (Urethane acrylate) As described above, the urethane acrylate contained in the curable composition of the present invention is an addition product of an isocyanate and at least one hydroxyl group-containing compound. In other words, the urethane acrylate compound can be described as a compound (addition product) having structural units derived from the isocyanate and structural units derived from the hydroxyl group-containing compound. Therefore, the urethane acrylate compound has a urethane bond (OCONH) and two or more (meth)acryloyl groups in its molecule. The urethane acrylate compound contains structural units derived from the isocyanate and structural units derived from the hydroxyl group-containing compound. The structural units derived from the hydroxyl group-containing compound are units formed by removing the hydrogen atom from the hydroxyl group in the hydroxyl group-containing compound.

[0035] The number average molecular weight of the urethane acrylate compound is preferably 500 or more and 3000 or less in terms of molar mass. The number average molecular weight of the urethane acrylate compound is preferably 800 or more, more preferably 900 or more, preferably 2500 or less, more preferably 2000 or less, even more preferably 1800 or less, and particularly preferably 1600 or less.

[0036] In this invention, the number-average molecular weight can refer to the value obtained by GPC measurement. Specifically, this is performed using a GPC apparatus with tetrahydrofuran (THF) as the solvent, and the value is determined as a polystyrene equivalent. The specific measurement conditions are as follows. Column: Polystyrene gel column manufactured by Tosoh Corporation (TSKgel G4000HXL + TSKgel G3000HXL + TSKgel G2000HXL + two TSKgel G1000HXL connected in series in this order) Column temperature: 40℃ Detector: Differential refractive index detector (RID-6A, manufactured by Shimadzu Corporation) Flow rate: 1ml / min

[0037] The method for obtaining urethane acrylate compounds by addition reactions is not particularly limited, and for example, known addition reaction conditions can be broadly employed in the present invention. For example, reaction conditions for reacting known alcohol compounds with isocyanate compounds can be broadly employed in the present invention.

[0038] In particular, the present invention prefers to employ an addition reaction using an isocyanate and an alcohol component containing at least one hydroxyl group-containing compound as raw materials. In this addition reaction, the isocyanate group (NCO) of the isocyanate reacts with the hydroxyl group (OH) of the hydroxyl group-containing compound in the alcohol component. This can produce a urethane acrylate compound.

[0039] The aforementioned alcohol component may include other compounds as long as it contains the aforementioned hydroxyl group-containing compound. Other compounds may include, for example, compounds that do not have a hydroxyl group but have two or more (meth)acryloyl groups. Hereinafter, compounds that do not have a hydroxyl group but have two or more (meth)acryloyl groups will be referred to as "Compound A".

[0040] Compound A is not particularly limited in type, as long as it does not have a hydroxyl group and has two or more (meth)acryloyl groups. In particular, it is preferable that the molecule has a skeleton derived from one or more compounds selected from the group consisting of pentaerythritol and dipentaerythritol. Specifically, examples of compound A include compounds in which all four hydrogen atoms of the hydroxyl groups of pentaerythritol are each replaced by (meth)acryloyl groups, and compounds in which all six hydrogen atoms of the hydroxyl groups of dipentaerythritol are each replaced by (meth)acryloyl groups.

[0041] Therefore, one embodiment of the alcohol component is one in which the hydroxyl group-containing compound and compound A are included.

[0042] The alcohol component may contain one or more of the hydroxyl group-containing compounds. Furthermore, if the alcohol component contains compound A, it may contain one or more of compound A. The alcohol component may consist solely of the hydroxyl group-containing compounds, or solely of the hydroxyl group-containing compounds and compound A.

[0043] When the alcohol component contains two or more of the aforementioned hydroxyl group-containing compounds, the content of each hydroxyl group-containing compound is not particularly limited, and for example, the content of each compound can be adjusted so that it falls within the hydroxyl value range described below. Furthermore, when the alcohol component also contains compound A, the content of each compound can be adjusted so that it falls within the hydroxyl value range described below.

[0044] For example, if the alcohol component contains one or more hydroxyl group-containing compounds having a skeleton derived from pentaerythritol, the content of such hydroxyl group-containing compounds is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less, based on the total mass of the hydroxyl group-containing compounds and compound A.

[0045] The hydroxyl value of the alcohol component can be, for example, 30 to 200 mg KOH / g. In order to form a coating film with particularly high Martens hardness and particularly excellent scratch resistance, the hydroxyl value of the alcohol component is preferably 40 mg KOH / g or more, more preferably 45 mg KOH / g or more, even more preferably 48 mg KOH / g or more, preferably 180 mg KOH / g or less, more preferably 160 mg KOH / g or less, even more preferably 140 mg KOH / g or less, and particularly preferably 130 mg KOH / g or less.

[0046] The method for producing the alcohol component is not particularly limited; for example, it can be produced by known methods, or it may be produced by separately preparing the desired hydroxyl group-containing compound and compound A as needed, and then mixing them.

[0047] In particular, in the present invention, the alcohol component can be prepared by a reaction, specifically a condensation reaction, between a compound having a (meth)acryloyl group and a polyol compound. Examples of compounds having a (meth)acryloyl group include carboxylic acid compounds having a (meth)acryloyl group, such as acrylic acid and methacrylic acid. Examples of polyol compounds include compounds having two or more hydroxyl groups, among which pentaerythritol and dipentaerythritol can be preferably used. In this case, the resulting alcohol component may contain a hydroxyl group-containing compound having a skeleton derived from one or more compounds selected from the group consisting of pentaerythritol and dipentaerythritol in its molecule.

[0048] When preparing the alcohol component by the condensation reaction described above, the reaction conditions are not particularly limited, and for example, known condensation reaction conditions can be widely used. In the condensation reaction, for example, known catalysts, polymerization inhibitors, solvents, etc., can be used. Since condensed water is generated by the above condensation reaction, this condensed water can be removed during the reaction as needed.

[0049] Polyol compounds are esterified by condensation reactions. In condensation reactions, the hydroxyl value of the polyol component can be adjusted to a desired range by controlling the ratio of esterified polyol to the total amount of polyol compound used.

[0050] The product obtained from the condensation reaction can be neutralized and purified using appropriate methods. This allows the desired alcohol component to be obtained.

[0051] Next, the addition reaction between the isocyanate and the alcohol component will be explained. Specifically, the addition reaction can be carried out by reacting the isocyanate and the alcohol component in the presence of a catalyst, thereby obtaining an addition product. The addition product is the reaction product of the isocyanate and the hydroxyl group-containing compound in the alcohol component.

[0052] Furthermore, if the alcohol component contains compound A, compound A does not participate in the addition reaction; that is, it is present in the product together with the resulting urethane acrylate compound.

[0053] As the catalyst, for example, organotin compounds can be used. Specific examples include tin octoate, dibutyltin dilaurate, dioctyltin dineodecanate, dioctyltin dilaurate, manganese, cobalt, lead, bismuth stanate, lead stanate, zirconium octoate, zinc octoate, dibutyltin-bis-o-phenylphenylene, dibutyltin-S,S-dibutyldithiocarbonate, triphenylantimony dichloride, dibutyltin maleate, dibutyltin diacetate, dibutyltin dilaurate mercaptide, triethylenediamine, bismuth stearate, lead stearate, and dimethyltin dichloride. The amount of catalyst used can usually be adjusted within a range of 0.001 to 5 parts by weight per 100 parts by weight of the total isocyanate and alcohol components.

[0054] Addition reactions can also be carried out in the presence of polymerization inhibitors. A wide range of known polymerization inhibitors, such as hydroquinone monomethyl ether, can be used as polymerization inhibitors.

[0055] The reaction temperature for the addition reaction is not particularly limited and can be, for example, around 30 to 100°C, preferably 50 to 80°C. The reaction time is also not particularly limited and can be set within an appropriate range depending on the reaction temperature. For example, the reaction can be carried out until the amount of free isocyanate is 10% by mass or less, preferably 5% by mass or less, and more preferably 0.1% by mass or less, relative to the isocyanate used.

[0056] As described above, the addition reaction proceeds, causing the isocyanate to react with the hydroxyl group-containing compound in the alcohol component, producing an addition product, namely a urethane acrylate compound. Note that if compound A is present in the alcohol component, compound A does not contain a hydroxyl group and therefore does not react with the isocyanate. Consequently, compound A remains after the addition reaction along with the resulting urethane acrylate compound.

[0057] In the addition reaction, the ratio of the total number of moles of hydroxyl groups to the total number of moles of isocyanate groups, i.e., the OH / NCO value, can be in the range of 0.5 to 2, preferably 0.8 to 1.5, and more preferably 0.9 to 1.3.

[0058] (Inorganic fine particles) The inorganic fine particles contained in the curable composition of the present invention have polymerizable unsaturated groups on their surface. More specifically, the inorganic fine particles are composed of core fine particles, and the surface of these core fine particles is modified with polymerizable unsaturated groups.

[0059] The type of core nanoparticles is not particularly limited; for example, various metal oxide nanoparticles can be used, specifically silica, titania, alumina, zinc oxide, zirconium oxide, tin oxide, etc. As described later, as long as the core nanoparticles are metal oxide nanoparticles, the effects of the present invention are not inhibited, that is, the coating film obtained from the curable composition of the present invention has higher Martens hardness and better scratch resistance. In particular, silica is preferred as the core nanoparticle because it is easier to form a coating film with higher Martens hardness and better scratch resistance.

[0060] The polymerizable unsaturated groups modified on the surface of the nuclear nanoparticles are preferably polymerizable functional groups, and are preferably radical polymerizable unsaturated groups in terms of versatility and reactivity. From this viewpoint, examples of polymerizable unsaturated groups include (meth)acryloyl groups, vinyl groups, allyl groups, styryl groups, maleimide groups, etc., with (meth)acryloyl groups being more preferable.

[0061] The polymerizable unsaturated groups modifying the surface of the nuclear nanoparticles are preferably chemically bonded to the surface of the nuclear nanoparticles, and in particular, it is preferable that the functional groups containing polymerizable unsaturated groups are bonded to the surface of the nuclear nanoparticles by covalent bonds. Such covalent bonds are formed, for example, by a chemical reaction between a functional group present on the surface of a metal oxide (e.g., a hydroxyl group, an amino group, a thiol group, etc.) and a compound containing a polymerizable unsaturated group. Examples of compounds containing polymerizable unsaturated groups include silane coupling agents having polymerizable functional groups, such as 3-(trimethoxysilyl)propyl methacrylate.

[0062] The method for modifying the surface of the core nanoparticles with polymerizable unsaturated groups is not particularly limited, and for example, known methods can be widely employed. Furthermore, the core nanoparticles whose surfaces are modified with polymerizable unsaturated groups, that is, the inorganic nanoparticles contained in the curable composition of the present invention, can be obtained from commercially available products, for example, commercially available organosols, and a specific example is Nissan Chemical's organosilica sol.

[0063] The median particle size of the inorganic microparticles is 15 to 75 nm, that is, the median particle size of the inorganic microparticles is between 15 nm and 75 nm. If the median particle size of the inorganic microparticles falls below 15 nm, the Martens hardness of the coating film formed from the curable composition of the present invention decreases, the coating film cannot obtain the desired hardness, and its scratch resistance also decreases. If the median particle size of the inorganic microparticles exceeds 75 nm, the Martens hardness of the coating film formed from the curable composition of the present invention decreases.

[0064] The median particle size of the inorganic fine particles is preferably 20 nm or larger, more preferably 25 nm or larger, even more preferably 30 nm or larger, particularly preferably 35 nm or larger, and also preferably 70 nm or smaller, more preferably 60 nm or smaller, even more preferably 55 nm or smaller, and particularly preferably 50 nm or smaller.

[0065] In this invention, the median particle size of inorganic fine particles refers to the value measured by converting the specific surface area measurement by the BET adsorption method to a perfect sphere. In this case, the specific surface area is measured in accordance with JIS-Z8830. However, if inorganic fine particles are obtained from a commercially available product and the manufacturer's guaranteed value or measured value of the median particle size is known, that value shall be adopted as the median particle size of the inorganic fine particles.

[0066] The shape of the inorganic fine particles is not particularly limited; for example, they can be spherical, ellipsoidal, or otherwise amorphous.

[0067] The inorganic fine particles contained in the curable composition of the present invention may be one type or two or more types.

[0068] The inorganic fine particles contained in the curable composition of the present invention may be dispersed in an organic solvent, for example. The organic solvent will be described later, but it can be the same type as the solvents that may be added to improve the coating properties of the curable composition of the present invention.

[0069] Because the curable composition of the present invention contains inorganic fine particles configured as described above, the curable composition of the present invention is more likely to form a coating film with higher Martens hardness and superior scratch resistance, and the substrate having such a coating film is less prone to phenomena such as curling. Furthermore, because the inorganic fine particles have polymerizable unsaturated groups on their surface, the curable composition of the present invention has high transparency.

[0070] While we do not necessarily desire a restrictive interpretation, during the curing process of the curable composition of the present invention, a urethane acrylate compound having a predetermined structure reacts with polymerizable unsaturated groups on the surface of inorganic microparticles, for example, through a radical polymerization reaction. That is, the inorganic microparticles can form copolymers with the urethane acrylate compound. As a result, the inorganic microparticles can firmly exist in the cured product (coating film) of the curable composition, meaning that detachment of the inorganic microparticles is less likely to occur. It is presumed that the effects of the present invention are exhibited as a result of this. Thus, since the effects of the present invention are exhibited by the composition of the present invention containing a predetermined urethane acrylate compound and copolymerizing with inorganic microparticles, the effects of the present invention are not inhibited as long as each of the inorganic microparticles is a metal oxide. In particular, when the core microparticles are silica, the Martens hardness becomes especially high, and it becomes easier to form a coating film with particularly excellent scratch resistance.

[0071] (Curable composition) The curable composition of the present invention contains a urethane acrylate compound and inorganic fine particles as essential components. As a result, the curable composition of the present invention easily forms a coating film with higher Martens hardness and superior scratch resistance, and the substrate having such a coating film is less prone to phenomena such as curling.

[0072] If the urethane acrylate compound is obtained using an alcohol component containing compound A as described above, compound A will remain unreacted in the addition reaction to obtain the urethane acrylate compound, and therefore, the curable composition of the present invention may also contain compound A.

[0073] In other words, the curable composition of the present invention may further contain an acrylate compound that does not contain hydroxyl groups. Here, it is preferable that the acrylate compound that does not contain hydroxyl groups has a skeleton in its molecule derived from one or more compounds selected from the group consisting of pentaerythritol and dipentaerythritol. Specifically, examples of acrylate compounds that do not contain hydroxyl groups include compounds in which the hydrogen atoms of each of the four hydroxyl groups of pentaerythritol are replaced by (meth)acryloyl groups, and compounds in which the hydrogen atoms of each of the six hydroxyl groups of dipentaerythritol are replaced by (meth)acryloyl groups.

[0074] In the curable composition of the present invention, the content of the urethane acrylate compound and inorganic fine particles is not particularly limited. For example, in the curable composition of the present invention, the content of inorganic fine particles per 100 parts by mass of the total mass of the urethane acrylate compound and compound A is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 30 parts by mass or more, particularly preferably 35 parts by mass or more, and also preferably 150 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 70 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0075] When the curable composition of the present invention contains compound A, the content of compound A is preferably 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 35 parts by mass or more, preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less, based on 100 parts by mass of the total mass of the urethane acrylate compound and compound A.

[0076] The curable composition of the present invention may contain other components in addition to the urethane acrylate compound, inorganic fine particles, and compound A, as long as the effects of the present invention are not inhibited. Examples of other components include solvents, polymerization initiators, polymerization inhibitors, photosensitizers, light stabilizers, silane coupling agents, ultraviolet absorbers, catalysts, leveling agents, defoamers, polymerization accelerators, antioxidants, flame retardants, infrared absorbers, antistatic agents, slip agents, plasticizers, dispersants, and the like.

[0077] The aforementioned solvent may be added, for example, to improve the coating properties of the curable composition of the present invention. Examples of solvents include chlorinated hydrocarbons such as chloroform and 1,2-dichloroethane; ether compounds such as diethyl ether and tetrahydrofuran; aliphatic hydrocarbons such as hexane and heptane; alicyclic hydrocarbons such as cyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; ketone compounds such as acetone and methyl ethyl ketone; ester compounds such as vinyl acetate; alcohols such as methanol, ethanol, isopropyl alcohol, and t-butanol; formamides such as N,N-dimethylformamide and N,N-dimethylacetamide; pyrrolidones such as 2-pyrrolidone and N-methylpyrrolidone; and dimethyl sulfoxides.

[0078] The amount of solvent contained in the curable composition of the present invention is not particularly limited. For example, the amount of solvent can be adjusted so that the total concentration of the curable component is 1 to 100% by mass. Considering the coating properties, it is preferably about 20 to 90% by mass, and more preferably 50% by mass or more.

[0079] The polymerization initiator can be, for example, any known polymerization initiator. The polymerization initiator may be either a thermal decomposition polymerization initiator or a photopolymerization initiator, and a photopolymerization initiator is preferred because it is easier to form a film.

[0080] Examples of photopolymerization initiators include aromatic ketones such as benzophenone, aromatic compounds such as anthracene and α-chloromethylnaphthalene, and sulfur compounds such as diphenyl sulfide and thiocarbamate. Examples of polymerization initiators using active energy rays other than visible light, such as ultraviolet light, include acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, xanthones, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzophenone, benzoin propyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2-hydroxy-2-methyl-1- Examples include phenylpropan-1-one, thioxanthone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and oligo(2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)propanone).

[0081] The content of the polymerization initiator in the curable composition of the present invention is not particularly limited and can be 0.01 to 10 parts by mass, preferably 0.03 to 5 parts by mass, based on 100 parts by mass of the total amount of the urethane acrylate compound and compound A.

[0082] When the curable composition of the present invention contains a photopolymerization initiator, the curable composition of the present invention has active energy ray curability and can be called an active energy ray curable composition. The active energy ray is preferably ultraviolet light, but other examples include electron beams, gamma rays, carbon arc lamps, xenon lamps, metal halide lamps, etc.

[0083] The total content ratio of the urethane acrylate compound, inorganic fine particles, and compound A relative to the total mass of solids in the curable composition of the present invention is preferably 60% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. The solids in the curable composition of the present invention can mean, for example, components excluding volatile components such as solvents.

[0084] In the curable composition of the present invention, the median particle size of the inorganic microparticles can be measured by the following procedure. The curable composition is separated into inorganic particles and other components using a centrifuge. The obtained inorganic microparticles are directly observed using a scanning electron microscope, 200 inorganic microparticles are selected from the captured image, and the average value of their equivalent circle diameters is taken as the median particle size of the inorganic microparticles in the curable composition.

[0085] The method for producing the curable composition of the present invention is not particularly limited. For example, the curable composition of the present invention can be prepared by mixing a urethane acrylate compound with inorganic fine particles. Alternatively, the curable composition of the present invention can be prepared by mixing a urethane acrylate compound, inorganic fine particles, and optionally included components in a predetermined ratio. Or, the curable composition of the present invention can be prepared by mixing the product obtained from the above-mentioned addition reaction (which may contain a urethane acrylate compound and possibly compound A), inorganic fine particles, and optionally included components in a predetermined ratio. The urethane acrylate compound and inorganic fine particles used to produce the curable composition of the present invention may both contain the aforementioned solvent.

[0086] In particular, the method for producing the curable composition of the present invention preferably includes a step of obtaining the urethane acrylate compound by an addition reaction between the isocyanate and the alcohol component (i.e., an alcohol component containing a hydroxyl group-containing compound). In this case, the alcohol component may contain compound A in addition to the hydroxyl group-containing compound. Furthermore, it is preferable that the alcohol component has the aforementioned hydroxyl value.

[0087] 2. Coating liquid and coating film A coating solution can be obtained using the curable composition of the present invention. For example, a coating solution containing the curable composition of the present invention can be prepared by blending the curable composition of the present invention with other components as needed. The coating solution may consist solely of the curable composition of the present invention.

[0088] A coating film can be formed using such a coating liquid. Specifically, a coating film can be formed on a substrate by applying the coating liquid to a substrate to form a film, and then curing the film. That is, the coating film contains a cured product of the coating liquid (it can be said that it contains a cured product of the curable composition of the present invention). The cured product contains a polymer of the urethane acrylate compound and the inorganic fine particles.

[0089] The substrate is not particularly limited, and various known resin films can be cited as examples. The type of film is also not particularly limited, and a wide range of resin films can be cited, such as polyethylene terephthalate film, polyethylene film, acrylic film, etc.

[0090] The method for applying the coating liquid obtained from the curable composition of the present invention onto a substrate is not particularly limited, and a wide range of known coating methods can be employed. For example, it can be applied using known coating equipment, such as blade coaters, air knife coaters, roll coaters, bar coaters, gravure coaters, microgravure coaters, rod blade coaters, lip coaters, die coaters, and curtain coaters.

[0091] The method for curing the film formed on the substrate is not particularly limited, and one example is to irradiate the film with the aforementioned active energy rays. The active energy rays are preferably ultraviolet rays, but other examples include electron beams, gamma rays, carbon arc lamps, xenon lamps, metal halide lamps, etc. The method and conditions for irradiating with active energy rays are also not limited and can be the same as those known. Examples of ultraviolet light sources include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, gallium lamps, metal halide lamps, sunlight, and ultraviolet lamps such as LEDs.

[0092] The thickness of the coating is not particularly limited and can be set within an appropriate range depending on the intended use.

[0093] The median particle size of inorganic microparticles in a coating can be measured using the following procedure. First, the coating is heat-treated to burn off the organic components, thereby separating the inorganic microparticles. The heat treatment is performed at 300°C for 3 hours in an atmospheric environment. The obtained inorganic microparticles are directly observed using a scanning electron microscope, 200 inorganic microparticles are selected from the captured image, their equivalent circle diameters are calculated, and the average value is taken as the median particle size of the inorganic microparticles in the coating.

[0094] As described above, the resulting coating film contains the cured product of the curable composition of the present invention, resulting in higher Martens hardness and superior scratch resistance. Furthermore, substrates coated with such a film are less prone to phenomena such as curling.

[0095] Therefore, the curable composition of the present invention and the coating liquid containing the composition are suitable for use as coating agents for forming a coating film on a substrate such as a resin film.

[0096] Various laminates can be formed using the aforementioned coating film, for example, a laminate having the coating film on a substrate. Such a laminate, by having the coating film, is less prone to scratching of the substrate surface and less prone to curling.

[0097] In identifying the inventions contained herein, the components (properties, structures, functions, etc.) described in each embodiment of this disclosure may be combined in any way. That is, this disclosure encompasses all subject matter consisting of any combination of the combinatable components described herein. [Examples]

[0098] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to the embodiments of these examples.

[0099] (Manufacturing example 1a: Alcohol component a (Hydroxyl value 50 mg KOH / g)) Addition reaction products with alcohol components containing hydroxyl group-containing compounds were synthesized by the following procedure. First, 3166 parts by mass (43.9 moles) of acrylic acid, 1526 parts by mass (6.0 moles) of dipentaerythritol, 187.7 parts by mass of p-toluenesulfonic acid, 9.4 parts by mass of hydroquinone monomethyl ether, and 939 parts by mass of toluene were added to a four-necked flask equipped with a thermometer, stirrer, and water-cooled condenser, and mixed. Then, under reduced pressure, the reaction was carried out while maintaining a reaction temperature of approximately 100°C with the addition of air until 88% of the total hydroxyl groups in the dipentaerythritol were esterified. The reaction was carried out while removing condensation water. After the reaction was complete, neutralization treatment was performed by adding 1.2 times the molar amount of a 25% by mass aqueous sodium hydroxide solution while stirring, thereby removing excess acrylic acid and p-toluenesulfonic acid. Subsequently, the organic layer was separated and washed with water by adding 25 parts by mass of water per 100 parts by mass of the organic layer while stirring. Subsequently, the organic layer was separated again, and toluene was removed by distillation under reduced pressure. This prepared alcohol component a containing a hydroxyl group-containing compound. The obtained alcohol component a was 3894 parts by mass, and its hydroxyl value was 50 mgKOH / g.

[0100] The obtained alcohol component a contained components (1) and (2) as shown below. Component (1) was a compound in which the hydrogen atoms of each of the five hydroxyl groups of dipentaerythritol were each replaced by acryloyl groups (i.e., a hydroxyl group-containing compound), and component (2) was a compound in which the hydrogen atoms of each of the six hydroxyl groups of dipentaerythritol were each replaced by acryloyl groups (i.e., compound A). The content ratios of component (1) and component (2) were 47% by mass and 53% by mass, respectively, as shown below. • Ingredients (1): Dipentaerythritol pentaacrylate (47% by mass) • Ingredients (2): Dipentaerythritol hexaacrylate (53% by mass) As described above, alcohol component a was obtained as a mixture of component (1) and component (2).

[0101] (Manufacturing example 1b: Alcohol component b (Hydroxyl value 120 mg KOH / g)) Addition reaction products with alcohol components containing hydroxyl group-containing compounds were synthesized by the following procedure. First, 1151 parts by mass (16.0 mol) of acrylic acid, 604 parts by mass (4.44 mol) of pentaerythritol (manufactured by Koei Chemical Industry Co., Ltd.), 43.9 parts by mass of p-toluenesulfonic acid, 2.1 parts by mass of hydroquinone monomethyl ether, and 552 parts by mass of toluene were added to a four-necked flask equipped with a thermometer, stirrer, and water-cooled condenser, and mixed. Then, under reduced pressure, the reaction was carried out while blowing air into the mixture and maintaining a reaction temperature of approximately 100°C until 83% of the total hydroxyl groups in the pentaerythritol were esterified. The reaction was carried out while removing condensation water. After the reaction was complete, 353 parts by mass of toluene were added. Neutralization treatment was performed by adding a 20% by mass aqueous sodium hydroxide solution, equivalent to 1.4 times the molar amount relative to the acidity of the reaction solution with added toluene, while stirring, thereby removing excess acrylic acid and p-toluenesulfonic acid. Subsequently, the organic layer was separated and washed with water by adding 10 parts by mass of water to 100 parts by mass of the organic layer while stirring. Then, the organic layer was separated again, and toluene was removed by distillation under reduced pressure. The obtained acrylate 1 was 1082 parts by mass and had a hydroxyl value of 120 mgKOH / g.

[0102] The obtained alcohol component b contained the following components (3), (4), and (5). Component (3) was a compound in which two hydrogen atoms of the hydroxyl groups of pentaerythritol were each replaced by acryloyl groups (i.e., a hydroxyl group-containing compound), component (4) was a compound in which three hydrogen atoms of the hydroxyl groups of pentaerythritol were each replaced by acryloyl groups (i.e., a hydroxyl group-containing compound), and component (5) was a compound in which four hydrogen atoms of the hydroxyl groups of pentaerythritol were each replaced by acryloyl groups (i.e., compound A). The content ratios of components (3), (4), and (5) were 6% by mass, 49% by mass, and 45% by mass, respectively, as shown below. • Ingredient (3): Pentaerythritol diacrylate (6% by mass) • Ingredients (4): Pentaerythritol triacrylate (49% by mass) • Ingredients (5): Pentaerythritol tetraacrylate (45% by mass) As described above, alcohol component b was obtained as a mixture of components (3), (4), and (5).

[0103] The proportions of each component in the aforementioned alcohol components a and b were determined by high-performance liquid chromatography (HPLC, "ProminenceiLC2050C" (Shimadzu Corporation)) analysis. Specifically, the measurements were performed using a column ("InertsilODS-2", inner diameter 4.6 mm x length 250 mm (GL Sciences Co., Ltd.)), column temperature 40°C, and a gradient elution method with methanol / water = 20 / 80 to 100 / 0 as the mobile phase.

[0104] (Production example 2a: Urethane acrylate compound 1) As the isocyanurate derivative of an aliphatic isocyanate, 13.8 parts by mass of HDI nurate ("Coronate HX" manufactured by Tosoh Corporation) was prepared, 0.05 parts by mass of hydroquinone monomethyl ether was prepared as a polymerization inhibitor, 0.02 parts by mass of dioctyl tin dieodecanate was prepared as a reaction catalyst, and 86.2 parts by mass of alcohol component a with a hydroxyl value of 50 mg KOH / g obtained in Production Example 1a was prepared and placed in a flask. The ratio of the total number of moles of hydroxyl groups to the total number of moles of isocyanate groups (i.e., the value of [OH] / [NCO]) was set to 1.1. HDI nurate has a nurate structure and is a derivative of hexamethylene diisocyanate. Subsequently, the contents of the flask were heated to 50-80°C and the addition reaction was carried out until the amount of free isocyanate was 0.1% or less. The product obtained from this addition reaction was diluted with 25 parts by mass of methyl ethyl ketone (MEK) to obtain the target urethane acrylate compound 1 (hereinafter referred to as "UA1"). The number-average molecular weight of the obtained UA1 was 1300.

[0105] (Manufacturing Example 2b: Urethane Acrylate Compound 2) As an aliphatic isocyanate, 14.1 parts by mass of HMDI (hexamethylene diisocyanate) was prepared, 0.05 parts by mass of hydroquinone monomethyl ether was prepared as a polymerization inhibitor, 0.02 parts by mass of dioctyl tin dieodecanate was prepared as a reaction catalyst, and 86.0 parts by mass of alcohol component b with a hydroxyl value of 120 mg KOH / g obtained in Production Example 1b was prepared and placed in a flask. The ratio of the total number of moles of hydroxyl groups to the total number of moles of isocyanate groups (i.e., the value of [OH] / [NCO]) was set to 1.1. The contents of the flask were then heated to 50-80°C and the addition reaction was carried out until the amount of free isocyanate was 0.1% or less. The product obtained from this addition reaction was diluted with 25 parts by mass of methyl ethyl ketone (MEK) to obtain the target urethane acrylate compound 2 (hereinafter referred to as "UA2"). The number-average molecular weight of the obtained UA2 was 1340.

[0106] (Manufacturing example 2c: Urethane acrylate compound 3) As an alicyclic isocyanate, 17.8 parts by mass of IPDI (isophorone diisocyanate), 0.05 parts by mass of hydroquinone monomethyl ether as a polymerization inhibitor, 0.02 parts by mass of dioctyl tin dyneodecanate as a reaction catalyst, and 82.2 parts by mass of alcohol component b with a hydroxyl value of 120 mg KOH / g obtained in Production Example 1b were prepared and placed in a flask. The ratio of the total number of moles of hydroxyl groups to the total number of moles of isocyanate groups (i.e., the value of [OH] / [NCO]) was set to 1.1. The contents of the flask were then heated to 50-80°C and the addition reaction was carried out until the amount of free isocyanate was 0.1% or less. The product obtained from this addition reaction was diluted with 25 parts by mass of methyl ethyl ketone (MEK) to obtain the target urethane acrylate compound 3 (hereinafter referred to as "UA3"). The number-average molecular weight of the obtained UA3 was 900.

[0107] (Manufacturing example 2d: Urethane acrylate compound 4) As an aromatic isocyanate, 7.1 parts by mass of XDI (m-xylylene diisocyanate), 0.05 parts by mass of hydroquinone monomethyl ether as a polymerization inhibitor, 0.02 parts by mass of dioctyl tin dieodecanate as a reaction catalyst, and 92.9 parts by mass of alcohol component a with a hydroxyl value of 50 mg KOH / g obtained in Production Example 1a were prepared and placed in a flask. The ratio of the total number of moles of hydroxyl groups to the total number of moles of isocyanate groups (i.e., the value of [OH] / [NCO]) was set to 1.1. The contents of the flask were then heated to 50-80°C and the addition reaction was carried out until the amount of free isocyanate was 0.1% or less. The product obtained from this addition reaction was diluted with 25 parts by mass of methyl ethyl ketone (MEK) to obtain the target urethane acrylate compound 4 (hereinafter referred to as "UA4"). The number-average molecular weight of the obtained UA4 was 1100.

[0108] (Manufacturing example 2e: Urethane acrylate compound 5) As the isocyanurate of an aliphatic isocyanate, 164.6 parts by mass of HDI-nurate (Tosoh Corporation's "Coronate HX"), 0.05 parts by mass of hydroquinone monomethyl ether as a polymerization inhibitor, 0.02 parts by mass of dioctyl tin dyneodecanate as a reaction catalyst, and 35.4 parts by mass of hydroxyethyl acrylate were prepared and placed in a flask. The ratio of the total number of moles of hydroxyl groups to the total number of moles of isocyanate groups (i.e., the value of [OH] / [NCO]) was set to 1.1. Subsequently, the contents of the flask were heated to 50-80°C and the addition reaction was carried out until the amount of free isocyanate was 0.1% or less. The product obtained from this addition reaction was diluted with 50 parts by mass of methyl ethyl ketone (MEK) to obtain the target urethane acrylate compound 5 (hereinafter referred to as "UA5"). The number-average molecular weight of the obtained UA5 was 1200.

[0109] (Inorganic fine particles) • Inorganic microparticles 1: Nissan Chemical Corporation organosilica sol "MEK-AC-4130Y" (medium particle size 45 nm, silica modified with polymerizable unsaturated groups, solid content concentration 30% by mass) • Inorganic microparticles 2: Nissan Chemical's organosilica sol "MEK-AC-2140Z" (medium particle size 12 nm, silica modified with polymerizable unsaturated groups, solid content concentration 40% by mass) • Inorganic microparticles 3: Nissan Chemical Corporation organosilica sol "MEK-AC-5140Z" (medium particle size 80 nm, silica modified with polymerizable unsaturated groups, solid content concentration 40% by mass) • Target inorganic microparticles: Nissan Chemical's organosilica sol "MEK-ST-L" (medium particle size 45 nm, silica without polymerizable unsaturated groups on the surface, solid content concentration 30% by mass)

[0110] (Example 1) The raw materials were prepared according to the formulation of Example 1 shown in Table 1. Specifically, 100 parts by mass (80 parts by mass in terms of solid content) of UA1 (urethane acrylate compound 1) obtained in Production Example 2a, 106.7 parts by mass (32 parts by mass in terms of solid content) of the inorganic fine particles 1, and 0.24 parts by mass of "Omnirad 184" manufactured by IGM Resins BV as a photopolymerization initiator were mixed in a flask to obtain a curable composition.

[0111] (Example 2) A curable composition was obtained in the same manner as in Example 1, except that UA2 obtained in Production Example 2b was used instead of UA1 obtained in Production Example 2a.

[0112] (Example 3) A curable composition was obtained in the same manner as in Example 1, except that UA3 obtained in Production Example 2c was used instead of UA1 obtained in Production Example 2a, and the amount of inorganic fine particles 1 used was changed to the amount shown in Table 1.

[0113] (Example 4) A curable composition was obtained in the same manner as in Example 1, except that UA4 obtained in Production Example 2d was used instead of UA1 obtained in Production Example 2a.

[0114] (Comparative Example 1) A curable composition was obtained in the same manner as in Example 1, except that inorganic fine particles 1 were not used.

[0115] (Comparative Example 2) A curable composition was obtained in the same manner as in Example 1, except that inorganic fine particles 1 was replaced with inorganic fine particles 2, and the amount of inorganic fine particles 2 used was changed to the amount shown in Table 1.

[0116] (Comparative Example 3) A curable composition was obtained in the same manner as in Example 1, except that inorganic fine particles 1 was replaced with inorganic fine particles 3, and the amount of inorganic fine particles 3 used was changed to the amount shown in Table 1.

[0117] (Comparative Example 4) A curable composition was obtained in the same manner as in Example 1, except that inorganic fine particles 1 were replaced with target inorganic fine particles, and the amount of target inorganic fine particles used was changed to the amount shown in Table 1.

[0118] (Comparative Example 5) A curable composition was obtained in the same manner as in Example 1, except that UA5 obtained in Production Example 2e was used instead of UA1 obtained in Production Example 2a.

[0119] (Comparative Example 6) A curable composition was obtained in the same manner as in Example 1, except that UA1 obtained in Production Example 2a was replaced with dipentaerythritol acrylate (hydroxyl value 50 mg KOH / g), and the amounts of inorganic fine particles 1 and polymerization initiator used were changed to the amounts shown in Table 1.

[0120] (Evaluation method) The curable compositions obtained in each example and comparative example were used as coating solutions, and the presence or absence of turbidity of these coating solutions was evaluated by the following method. Furthermore, coating films were prepared using these coating solutions by the following method, and their Martens hardness, scratch resistance, and pencil hardness were evaluated. Additionally, the curlability of the obtained coating solutions was evaluated by the following method.

[0121] (Presence or absence of cloudiness in the coating solution) The curable compositions obtained in each example and comparative example were used as coating liquids. The presence or absence of cloudiness in these coating liquids was determined by visually observing their appearance and evaluated according to the following criteria. If the coating liquid was cloudy, no further evaluation was performed. ○: The coating liquid was visually confirmed to be transparent. ×: The coating solution was observed to be cloudy.

[0122] [Preparation of coating film] The curable compositions obtained in each example and comparative example were used as coating liquids and applied to a 100 μm thick PET film (Toyobo Co., Ltd.'s "Cosmoshine A4360") to a dry film thickness of approximately 5 μm. The film was then dried in an 80°C oven for 1 minute to form a coating on the PET film. Subsequently, under a nitrogen atmosphere, a high-pressure mercury lamp (80 W / cm x 1 lamp) was used to achieve an integrated illuminance of 600 mJ / cm². 2 The coating was cured by irradiating it with a PET film, and a laminate was obtained in which a coating film was formed on the PET film.

[0123] [Martens hardness HM] The Martens hardness (N / mm²) of the aforementioned coating film 2 The hardness of the coating was evaluated by measuring the microhardness using an indentation test with an Elionix microhardness tester (product number: ENT-1100a). The indentation test was performed with an indentation load of 0.3 mN. The indentation test was conducted in accordance with the indentation test method compliant with ISO 14577-1, and the triangular pyramidal indenter used had a ridge spacing of 115 degrees. The Martens hardness (HM) was calculated using the formula HM = F / As(h), that is, the value obtained by dividing the maximum load (F) by the surface area of ​​the indenter (As(h)) calculated from the maximum indentation depth of the indenter. A higher Martens hardness (HM) value indicates a higher hardness coating.

[0124] [Pencil hardness] The coating on the surface of the laminate was tested in accordance with JIS K5400. Specifically, using a pencil scratch tester, the coating was scratched sequentially with pencils of different hardnesses under a load of 750g. The hardness of the hardest pencil that did not scratch the coating was defined as the pencil hardness of the coating.

[0125] [Scratch resistance] Using #0000 steel wool on the coating film formed on the surface of the laminate, a load of 250 g / cm² was applied. 2 A scratch resistance test was conducted under the condition of 1000 back-and-forth strokes of 6 cm, and the surface of the laminate after the test was visually inspected and the scratch resistance was evaluated according to the following criteria. ≪Judgment criteria≫ A: It has two or fewer scratches and exhibits excellent scratch resistance. B: Has 3 to 4 scratches, indicating poor scratch resistance. C: Has 5 or more scratches, indicating extremely poor scratch resistance.

[0126] [Curling] The coating solution was applied to a 100 μm thick PET film ("Cosmoshine A4360," manufactured by Toyobo Co., Ltd.) to a dry film thickness of approximately 10 μm. Then, under a nitrogen atmosphere, a high-pressure mercury lamp (80 W / cm x 1 lamp) was used to achieve an integrated illuminance of 600 mJ / cm². 2 By irradiating with [a specific light source], a laminate was obtained in which a coating film was formed on a PET film. The obtained laminate was cut to a size of 6 cm x 6 cm, placed on a horizontal surface, and one corner was fixed. The height (mm) of each of the three corners from the horizontal surface was measured, and the average value was calculated. A smaller average value indicates less warping and superior low-curl properties.

[0127] Table 1 shows the preparation conditions and evaluation results (presence or absence of cloudiness in the coating solution, Martens hardness, pencil hardness, scratch resistance, and curling properties) for the curable compositions obtained in each example and comparative example. A blank space in Table 1 indicates that the raw material was not used.

[0128] Table 1 shows that the coatings obtained using the curable compositions prepared in each example have high hardness. Specifically, the coatings obtained using the curable compositions prepared in each example have high Martens hardness and pencil hardness, excellent scratch resistance, and can also suppress curling of the substrate.

[0129] [Table 1]

Claims

1. A curable composition comprising a urethane acrylate compound and inorganic fine particles, The urethane acrylate compound is an addition reaction product of an isocyanate and at least one hydroxyl group-containing compound. The isocyanate is a bifunctional or trifunctional isocyanate compound. The hydroxyl group-containing compound has at least two (meth)acryloyl groups and at least one hydroxyl group in its molecule. The inorganic fine particles have polymerizable unsaturated groups on their surface, A curable composition in which the median particle size of the inorganic fine particles is 15 to 75 nm.

2. The curable composition according to claim 1, wherein the hydroxyl group-containing compound has a skeleton in its molecule derived from one or more compounds selected from the group consisting of pentaerythritol and dipentaerythritol.

3. The curable composition according to claim 1, further comprising an acrylate compound that does not contain a hydroxyl group.

4. The curable composition according to claim 3, wherein the acrylate compound that does not contain a hydroxyl group has a skeleton in the molecule derived from one or more compounds selected from the group consisting of pentaerythritol and dipentaerythritol.

5. A coating liquid containing the curable composition according to claim 1 or 2.

6. A coating film containing a cured product of the coating liquid described in claim 5.

7. The coating film according to claim 6, wherein the cured product contains a polymer of the urethane acrylate compound and the inorganic fine particles.

8. A laminate comprising a coating film according to claim 7 on a substrate.

9. A method for producing a curable composition according to any one of claims 1 to 4, A method for producing a curable composition, comprising the step of obtaining the urethane acrylate compound by performing an addition reaction between the isocyanate and an alcohol component containing the hydroxyl group-containing compound.

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